Blasting cap



Oct. 10, 1933. J. BARAB 1,929,911

BLASTING CAP Filed March 9, 1932 to use of blasting caps of the electrically fired Patented Oct. 10, 1933 PATENT" OFFICE BLASTING CAP Jacob Barab, Wilmington, DeL,

Hercules Powder Company, Wilmington, Del.,

assignor to I a corporation of Delaware Application March 9, 1932. Serial No. 597,677

'1 Claims.

This invention relates to an improvement in blasting caps and more particularly relates to an arrangement for the protection, during shipment, in storageand in handling preparatory type.

As is well known blasting caps of the electrically fired type comprise a casing charged ,with explosive, as for example, fulminate of mercury, and forming the cap proper and a pair of lead wires extending from a bridge or heating wire within the casing for connection into an electric circuit. The ,lead wires are of a varying length, a common one being eight feet, and are insulated except for a portion at their free ends which is uninsulated in order that they may be readily connected into a circuit.

Blasting caps of the type indicated present substantial danger in shipment, storage and handling due to their sensitivity, i. e., the sensitivity of the explosive charge, as fulminate of mercury, which is likely to be fired by a jar, shock or impact and due to the possibility, more especially in handling, of the uninsulated ends of the lead wires coming into contact with a live circuit or receiving a stray current, which will effect firing of the cap.

Heretofore various arrangements have been provided for the protection of blasting caps against inadvertent firing either electrically or through shock. Thus various shunts have been provided for engagement with the uninsulated portions of the lead wires, but such have not in all cases proved satisfactory since, for example, variously their use results in distortion of the end portions of the wires making their proper connection into a circuit diflicult. For the protection of the cap proper against shock or jar it has been proposed to encase the cap, but such is not entirely satisfactory unless the lead wires are also shunted as by the provision of a shunt or by twisting uninsulated ends of the wires together with resultant distortion.

Now in accordance with this invention there is provided an arrangement whereby blasting caps will be adequately protected from shock or jar and from inadvertent electrical firing, the arrangement being such that the caps may be quickly and readily prepared for use and such that distortion of the lead wires will be positively avoided,

Having now indicated in a general way the nature and purpose of this invention, I will proceed to a detailed description of a preferred embodiment thereof with reference to the accompanying drawing in which:

Figure-1 is a view showing a protector and cap for assembly in accordance with my invention.

Figure 2 is side view partly broken away of the protector and cap assembled, a casing for the assembly being shown.

.In the several figures A indicates a blasting cap 013 any usual or desired type and equipped with a pair of lead wires B insulated except for their free end portions which are uninsulated as shown at c.

D indicates a protector or casing which may be of any suitable material, preferably non-conductive of electricity, such as, for example, paper lfibre, bakelite, wood, cloth covered metal, etc., etc. The protector D will have a longitudinal bore e and may be of any desired shape, in cross sections, as polygonal, and desirably though not necessarily will be provided with end flanges f, 3. Where the protector is provided with end flanges a notch Q will desirably be formed in one or both of the flanges.

In assembling the protector and cap the uninsulated free end portions 0 of the lead wires B will be placed on the protector adjacent one end and secured, if desired by means of a staple 1 which will act to shunt or short-circuit the lead wires and the lead wires wrapped thereover about the protector from .end to end, the cap A being finally inserted in the bore e. Where the protector is provided with end flanges, such will serve to retain the turns or wraps of the lead wires on the protector, preventing them from raveling, and where one of the flanges is provided with a notch g the lead wires will lie in the notch when the cap is positioned in the bore e.

If desired the protector may be provided with a cover a: into which the protector may be slipped.

As will now be noted by the arrangement embodying this invention, the uninsulated end porlo tions of the lead wires'are fully protected by the insulated portions of the wires wrapped thereover and the cap is protected from shock or jar by the protector and the wrapping of the lead wires thereover.

In order properly to uncoil the wires from detonator packages, it is necessary to unwind ditferently than in my method, for example, with those having the bare ends of the wire exposed it is necessary to insert into the hollow center 11 bore hole need the wires be unwound further of the package a lead pencil or the like and then unwind by pulling on the exposed ends of the wire, whereas with my package it is unnecessary to put such an axle inside the spool, particularly when I use flanges to prevent raveling while unwinding.

As will be noted the cap, fully protected, may be carried to the point of use and then readily removed from the protector by merely withdrawing it from the bore e and in unwinding the lead wires, which may be readily accomplished by holding spool in one hand and pulling cap lid with other. The lead wires, when wrapped about the protector, will be guarded iromdistortion and cannot become distorted in their removal therefrom.

The primer, i. e., the dynamite cartridge containing the electric blasting cap, 'may be made up without entirely uncoiling the cap wires from my package. It is necessary onlyto unwind a suflicient amount of lead wire to enable such a priming cartridge to be prepared and only when such priming cartridge is being placed in the and the spool left hanging on the outside of the bore hole until the time comes to remove the spool and connect the lead wires'to the firing circuit. When the ends of the lead wires are secured to the protector, as by a metal staple y accidental firing of the cap will positively be prevented, since the staplewill act to shunt the wires, even though they be entirely unwound from the protector, until it is desired to connect them into a circuit.

What I claim and desire to protect by Letters Patent is:

1. In combination a casing, a blasting cap within the casing and a pair of lead wires insulated except at their free end portions extending from the cap, the lead wires as a pair being wound upon themselves about the casing from their free ends with wraps of the insulated portions of the wires overlying the uninsulated free end portions.

2. In combination a cylindrical casing having a longitudinal bore and end flanges, a blasting cap within said bore, a. pair of lead wires insulated except for their free end portions extending from the cap, the lead wires being wound upon themselves about the casing from their free ends with wraps of the insulated portions of the wires overlying the uninsulated free end portions.

3. In combination a cylindrical casing having a longitudinal bore and end flanges, one or both of which is notched, a blasting cap within said bore and a pair of lead wires insulated except for their free end portions extending from the cap and laying in said notch, the lead wires being wound upon themselves about the casing from their free ends.

4. In combination a casing, a blasting cap within the casing and a pair of lead wires insulated except at their free end portions extending from the cap, the lead wires being securedto the casing through the medium of a conducting. member adapted to shunt them and being wound upon themselves about the casing from their free ends.

5. In combination a cylindrical casing having a longitudinal bore, a blasting cap within said bore, a pair of lead wires insulated except for their free end portions extending from the cap,

means for short circuiting the uninsulated end portions of the lead wires and the lead wires as a pair being wound upon themselves about the casing from their free ends with wraps of the insulated portions of the wires overlying the uninsulated free end portions.

6. In combination a casing, a blasting cap within the casing and a pair of lead wires insulated except at their free end portions extending from the cap, the lead wires as a pair being wound upon themselves about the casing from their free ends with-wraps of the insulated portions of the wires overlying the uninsulated free end portions, and protective means for the wrapped lead wires.

7. In combination a casing, a blasting cap within the casing and a pair of lead wires insulated except at their free end portions extending from the cap, the lead wires as a pair being wound upon themselves about the casing from their free ends with wraps of the insulated portions of the wires overlying the uninsulated free end portions, and a cover" embracing the casing and lead wires wrapped thereon.

JACOB BARAB. 

